This invention relates to Stirling cycle refrigerators in general and in particular to split Stirling cycle refrigerators used to provide cryogenic cooling.
In devices of this type, one of the principal problems of the prior art has been to isolate the cycle fluid from contamination sources generally associated with the driving mechanism of the device. For example, if a piston is used for displacing the cycle fluid the material used for lubricating the piston in its cylinder will generally contaminate the cycle fluid. Likewise where the activating device is a pneumatic device the driving fluid must be effectively sealed from the cycle fluid to prevent contamination. Still other devices have attempted to solve this problem through the use of a bellows which is cyclically compressed and expanded by means of a mechanical driving device. Such a device is disclosed in U.S. Pat. No. 3,765,187. While the bellows device provides an effective seal for the cycle fluid compartment, the bellows often demonstrate a short life under the extreme cyclical conditions and frequently provide reliability problems because of the difficulty in maintaining fluid integrity of the bellows. Thus prior art devices have suffered from contamination problems or reliability problems which have limited the applicability of such devices.